Endocardial mapping and ablation system utilizing a separately controlled ablation catheter and method

ABSTRACT

Endocardial mapping and ablation system for introduction into a chamber of a heart formed by a wall and having a passage leading thereto. The system is comprised of a catheter probe having a distal extremity. A plurality of electrodes are carried by the distal extremity for mapping the wall of the chamber. An ablation catheter is provided having a distal extremity. The ablation catheter has control capabilities whereby the distal extremity can be bent separately of movement of the catheter probe to come into close proximity to the wall of the heart. The distal extremity of the ablation catheter is provided with capabilities for ablating a portion of the wall of the heart to eliminate an arrythmia in the heart.

This is a continuation of application Ser. No. 08/439,663 filed May 11,1995, now U.S. Pat. No. 5,578,007, which is a continuation ofapplication Ser. No. 08/206,463 filed Mar. 4, 1994, abandoned, which isa division of application Ser. No. 07/894,529 filed Jun. 5, 1992, nowU.S. Pat. No. 5,324,284.

This invention relates to an endocardial mapping and ablation systemutilizing a separately controlled ablation catheter.

In co-pending application Ser. No. 07/656,764 filed Feb. 15, 1991 nowU.S. Pat. No. 5,156,161, there is disclosed an endocardial mappingand/or ablation system which includes a plurality of longitudinally andradially spaced apart electrodes which are utilized for mapping and alsowhich can be utilized for ablation. However, a need has arisen wherebyit is desirable to be able to provide ablation which is independent ofthe electrodes carried by the mapping and or ablation system. There istherefore a need for a new and improved endocardial mapping and/orablation system which overcomes this disadvantage.

In general, it is an object of the present invention to provide anendocardial mapping and ablation system and method which utilizes aseparately controlled ablation catheter.

Another object of the invention is to provide a system, catheter andmethod of the above character in which the distal extremity of theablation catheter can be independently controlled.

Another object of the invention is to provide a system, catheter andmethod of the above character in which once the site where the arrythmiaoriginates has been located, the ablation catheter can be steeredseparately to that location to perform an ablation.

Another object of the invention is to provide a system, catheter andmethod of the above character in which radio frequency energy can bedelivered to perform the ablation.

Another object of the invention is to provide a system, catheter andmethod of the above character in which laser energy can be delivered toperform the ablation.

Another object of the invention is to provide a system, catheter andmethod of the above character which can be utilized for delivering pulselaser energy for performing the ablation.

Another object of the invention is to provide a system, catheter andmethod of the above character which includes a cannula for delivering achemical into the heart muscle to perform the desired ablation.

Another object of the invention is to provide a system, catheter andmethod of the above character in which ablation can be accomplishedwithout interfering with an electrocardiogram.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiments are set forthin detail in conjunction with the accompanying drawings.

FIG. 1 is a side elevational view of an endocardial mapping and ablationsystem utilizing a separately controlled ablation catheter incorporatingthe present invention.

FIG. 2 is a cross-sectional view taken along the line 2--2 of FIG. 1.

FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG. 1.

FIG. 4 is a cross-sectional view similar to FIG. 3 showing the use of anablation catheter which has a capability of delivering pulsed laserenergy for ablation.

FIG. 5 is a cross-sectional view also similar to FIG. 3 which shows theuse of a retractable cannula for delivery of a chemical for ablation.

In general, the endocardial mapping and ablation system with aseparately controlled ablation catheter is for introduction into achamber of the heart of a patient with the heart being formed by a walland with the heart having a passage leading to the chamber. A catheterprobe is provided which has proximal and distal extremities. A pluralityof electrodes are carried by the distal extremity of the catheter probefor mapping the wall of the chamber. An ablation catheter is providedwith its distal extremity being disposed in the distal extremity of thecatheter probe. Control means is provided for the ablation catheterwhereby the distal extremity can be moved independently and separatelyof movement of the catheter probe to move the distal extremity intoclose proximity to the wall of the heart. Means is carried by the distalextremity of the ablation catheter for performing an ablation operationin the desired location in the wall of the heart.

More in particular, the mapping and ablation system 11 of the presentinvention consists of a catheter probe 12 and an ablation catheter 13.The catheter probe 12 is described in detail in co-pending applicationSer. No. 07/656,764 filed Feb. 15, 1991 now U.S. Pat. No. 5,156,161. Asdescribed therein, it is comprised of a flexible elongate member 16formed of a suitable material such as plastic which is provided withproximal and distal extremities 17 and 18. The flexible elongate member16 is provided with a centrally disposed lumen 21 extending the lengththereof. It should be appreciated that although the lumen 21 is shown asbeing centrally disposed, it can be offset if desired. Also, it isprovided with a plurality of additional lumens such as lumens 22 and 23,which also extend the length of the flexible elongate member 16. Ifdesired, still further additional lumens can be provided. As describedin said co-pending application Ser. No. 07/656,764 filed Feb. 15, 1991,now U.S. Pat. No. 5,156,161 the catheter probe 12 includes a pluralityof longitudinally and radially spaced apart electrodes 26. Expandablemeans 27 is secured to the distal extremity of the flexible elongatemember 16 for mounting the electrodes 26. The expandable means 27 asshown is formed of a plurality of flexible arms 28 which are movablebetween a contracted position and an expanded position. The proximalextremities of the arms 28 are secured to the distal extremity of theflexible elongate member 16. The distal extremities of the arms 16 aresecured within a cylindrical tip 29 which is provided with a rounded orhemispherical distal extremity.

Means is provided for moving the expandable means 27 between expandedand contracted positions and consists of a pull wire 31 which has itsdistal extremity secured within the cylindrical tip 29 and which extendsbetween the arms 28 through the lumen 22 of the flexible elongate member16, out the distal extremity of the member 16. This permits manualoperation of the pull wire 31 exterior of the human body containing theheart. The movement of the distal extremity of the expandable means 27in moving from an expanded position to a contracted dotted-line positionis shown in FIG. 1. It can be seen that by pulling on the pull wire 31,the tip 29 is pulled rearwardly or to the left as viewed in FIG. 1 tocause expansion of the expandable means whereby pushing of the pull wire31 forwardly or to the right as viewed in FIG. 1 will cause contractionof the same.

The electrodes 26 are connected to conductors 34 provided in a cable 36which extends through the lumen 23 of the flexible elongate member 16.The cable 36 is connected to a computer 37 which is provided with avideo screen 38.

The ablation catheter 13 is a separate component and is slidably mountedin the lumen 21 of the flexible elongate member 16 of the catheter probe12. Alternatively, it can be positioned independently of the catheterprobe 12 along side the catheter probe 12. The ablation catheter 13 iscomprised of a flexible elongate member 41 formed of a suitable materialsuch as a medical grade plastic. It is provided with a centrallydisposed or larger lumen 42 and six additional lumens 43-48 which aregenerally equally circumferentially spaced around the central lumen 42.The lumens 43, 45 and 47 are offset by approximately 120° with respectto each other. A conductor 51 of a suitable conducting material such ascopper and covered by an insulating layer 52 is disposed in the centrallumen 42 and, when RF energy is used for ablation, is connected to ahemispheric electrode 54 mounted on the tip or distal extremity 56 ofthe flexible elongate member 41. This same conductor can also beutilized for sensing for an electrocardiogram. This conductor 51 canalso serve as a stiffening element for the flexible elongate member 41,if that is desired.

The flexible elongate member 41 is provided with a proximal extremitythrough which the conductor 51 extends, which can be connected to thecomputer 37 and, alternatively or in addition, to a power supply andcontrol console 61 as shown by the dotted lines.

Means is provided for causing bending movement of the distal extremityof the flexible elongate member 41 and consists of flexible elongateelements 63, 65 and 67 which are disposed in the lumens 43, 45 and 47.These flexible elongate elements are formed of a material having anegative coefficient of expansion and are of the type described inco-pending application Ser. No. 07/793,858 filed Nov. 18, 1991 now U.S.Pat. No. 5,258,005. As described therein, one material suitable for thispurpose is a nickel titanium alloy manufactured and sold under thetrademark Flexinol by Toki of Japan. As explained in said co-pendingapplication, the heating of the Flexinol wire changes its crystallinestructure causing it to shorten itself, or in other words to have anegative coefficient of expansion upon the application of heat to thesame. These elements 63, 65 and 67 can be heated by passing electricalcurrent therethrough. This is accomplished by the use of three separateconductors 73, 75 and 77 which are bonded to the proximal extremities ofthe flexible elongate elements 63, 65 and 67 in the manner described inco-pending application Ser. No. 07/793,858 filed Nov. 18, 1991. Theconductors 73, 75 and 77 are provided with insulation 78 and aredisposed in the lumens 43, 45 and 47. All of them are connected to thepower supply and control console 61.

The distal extremities of the flexible elongate elements 63, 65 and 67are bonded together in a suitable manner and are connected to a groundconductor 81 having insulation 82 thereon. The conductor 81 is disposedin the lumen 46 and extends the length thereof. It is also connected tothe power supply and control console 61 to provide a ground return forthe flexible elongate elements 63, 65 and 67.

Operation and use of the endocardial mapping and ablation systemutilizing a separately controlled ablation catheter and the method ofusing the same may be briefly described as follows. The system is usedin a conventional manner as described in co-pending application Ser. No.07/656,764 filed Feb. 15, 1991 now U.S. Pat. No. 5,156,161. The catheterprobe 12 can be introduced through the superior or inferior vena cavaeinto the right atrium and then advanced into the right ventricle,assuming that is the desired cavity of the heart (not shown) or into theleft ventricle via the aorta. The cavity is formed by a wall of theheart and has a passage leading thereto as hereinbefore described. Thepull wire 31 is then pulled to cause the expandable means 27 with theelectrodes 26 carried thereby to be moved into engagement with the wallof the heart. The computer 37 is then utilized to map the variouspotentials within the wall forming the cavity of the heart and anisochronal map thereof is displayed on the computer screen 38. As soonas the focus of the arrythmia has been located, the user, i.e. thephysician, identifies the particular electrode of the electrodes 26where ablation energy is to be delivered. Rather than deliveringablation energy through the selected electrode 26, ablation is achievedin the present invention by the use of the separately controlledablation catheter 13.

The ablation catheter 13 is advanced through the lumen 21 by visualizingthe same, as for example by visualizing the tip electrode 54 withx-rays. It should be appreciated that if desired, additional markers canbe provided on the tip if necessary to provide adequate visualizationwith x-rays. As the ablation catheter 13 is being advanced into thechamber of the heart and into the expandable means 27, it can be bent inthe desired direction by the use of the control console 61 which is ofthe type described in co-pending application Ser. No. 07/793,858 filedNov. 18, 1991, now U.S. Pat. No. 5,258,005. Operation of the controlconsole 61 causes heating of the appropriate Flexinol wires 63, 65 and67 to cause bending of the distal extremity 56 of the flexible elongatemember 41 in the desired direction until the portion of the wall of theheart which is to be ablated is approached so that it is in closeproximity or in contact therewith. Typically the electrode 54 will begenerally flush with the arm 28 which carries the electrode 26 in theclosest proximity to the region to be ablated. As soon as the ablationcatheter 13 has been manipulated so that the electrode 54 is in thedesired position, ablation energy is caused to be delivered through theablation conductor 51 to the electrode 54 and through the return groundconductor to create an ablation in the tissue of the wall of the heartwhich is the focus of the arrythmia. By this ablation, the arrythmiashould be eliminated. Thereafter the ablation catheter 13 and thecatheter probe 12 can be removed.

It should be appreciated that the distal extremity 56 of the ablationcatheter can be bent in various directions extending about 3600 of thelongitudinal axis of the ablation catheter 13. In this way, it ispossible for the distal extremity 56 of the separately controlledablation catheter 13 to be moved into contact with any portion of thewall of the heart in the chamber in which the catheter probe 12 isdisposed and contacted by one of the electrodes 26.

It should be appreciated that the computer 37 can be utilized forautomatically positioning the distal extremity of the ablation catheter13. The computer collects the information from the electrodes 26 and theexpandable means 27 and displays them on the isochronal map on thecomputer screen 38 of the wall of the chamber of the heart in which theexpandable means 27 is disposed. The physician utilizing the isochronalmap identifies the particular electrode where ablation energy is to bedelivered. The computer 37 operates with the power supply 61 tomanipulate the distal extremity of the ablation catheter to bring thedistal extremity adjacent to the electrode selected by the physician.Once the distal extremity of the ablation catheter 13 is near theelectrode selected by the physician, the computer starts matching theelectrocardiogram signal picked up from the tip of the ablation catheter13 and the electrode selected on the expandable means 27. Once a matchis achieved, radiofrequency ablation energy is delivered from the powersupply 61 to the electrode 54 to cause the desired ablation to occur.After the ablation has been performed, the ablation catheter 13 and thecatheter probe can be removed.

One of the principal advantages of utilizing a separately controlledablation catheter 13 is that means other than RF energy can be utilizedfor performing an ablation. For example, as shown in FIG. 4, in place ofthe center conductor 51, a fiber optic 86 can be provided which extendsthrough the lumen 42 with the lumen 42 extending through the distalextremity of the flexible elongate member 41 to permit pulsed laserenergy to be delivered to the ablation site. By way of example, pulsedlaser energy can be delivered from an excimer laser through pure silicafibers serving as the fiber optic 86 to deliver such pulsed energy tothe ablation site. In such an arrangement, it may be desirable to placeanother conductor 87 in the lumen 44 which can serve as a conductor toan ECG sensing electrode which can be connected into the computer 37.

Another alternative for delivering ablation means to the wall of theheart is shown in FIG. 5 and consists of an ablation catheter 91 inwhich a retractable cannula 92 is disposed in the lumen 42. Theretractable cannula can be of the type described in co-pendingapplication Ser. No. 07/656,764 filed Feb. 15, 1991. now U.S. Pat. No.5,156,161. The cannula 92 can be advanced under the control of thecontrol console 61 and, after an appropriate incision has been made intothe tissue of the wall of the heart, a chemical can be introduced intothe incision by utilizing the centrally disposed lumen 93 providedcentrally within the cannula 92. A controlled amount of the chemical canbe delivered to the desired site to cause the desired amount of ablationof tissue of the heart.

The means for ablation provided in FIGS. 4 and 5 has an advantage overthe RF energy which is delivered in the embodiment shown in FIGS. 1, 2and 3 because it makes it possible to observe the electrogram on thescreen 38 during the time that the ablation is taking place, and tothereby ascertain when the arrythmia disappears. This is generally notpossible when radio frequency energy is used for ablation because theradio frequency interferes with the electrocardiogram being produced, sothat it is difficult, if not impossible, to observe the same on thescreen 38. Thus it can be seen that there is a distinct advantage inusing means other than RF energy for causing ablation in the wall of theheart.

In view of the foregoing, it can be seen that there has been provided anendocardial mapping and ablation system utilizing a separatelycontrolled ablation catheter which facilitates performing preciseablations after the mapping operation has been completed. By the use ofchemicals and/or laser energy, it is possible to perform such ablationswhile observing the electrocardiogram, thereby giving the physician theopportunity to ascertain when ablation should be discontinued bynoticing the disappearance of the arrythmia.

What is claimed is:
 1. A catheter system for mapping and ablation withina chamber of the heart formed by a wall having an inner surfacecomprising a plurality of flexible arms and an ablation electrodepositioned within the chamber, said flexible arms having distalextremities and connected at the distal extremities to form a basketconfiguration, each of said arms including a plurality of mappingelectrodes, said arms being expandable into contact with the innersurface to facilitate mapping, said ablation electrode including asupport for carrying said ablation electrode and for adjusting theposition of the ablation electrode independently of the flexible arms tobring the ablation electrode into engagement with the inner surfacewhile maintaining the flexible arms of the basket in engagement with theinner surface.
 2. A catheter system as in claim 1 wherein said supportis in the form of a separate catheter movable independently of theflexible arms of the basket.
 3. A method for endocardial mapping andablation utilizing a catheter system for introduction into a chamber ofa heart formed by a wall having an inner surface, said catheter systemincluding an expandable basket with a plurality of arms, each armcarrying a plurality of mapping electrodes, said catheter system furtherincluding at least one ablation electrode, the method comprising thesteps of expanding the basket so that the arms come into contact withthe inner surface, performing a mapping operation using the mappingelectrodes carried on the arms, independently moving the ablationelectrode to a desired location on the inner surface while maintainingthe position of the arms of the basket and ablating the wall having theinner surface using the ablation electrode.
 4. A method for endocardialmapping and ablation of the wall of the heart forming a chamber thereinand having a passage leading thereto by utilization of a catheter probeincluding an expandable basket with a plurality of arms having aplurality of mapping electrodes carried by the plurality of arms and anablation catheter, introducing the catheter probe into the chamber ofthe heart, performing mapping operations with the catheter probe byexpanding the expandable basket to bring the mapping electrodes of thecatheter probe into engagement with the wall of the heart inspaced-apart positions to ascertain the focus of an arrhythmia in theheart, thereafter independently manipulating the distal extremity of theablation catheter while the mapping electrodes are in the chamber of theheart so that the distal extremity of the ablation catheter is broughtinto close proximity to the focus of the arrhythmia and utilizing theablation catheter for ablating tissue of the wall of the heart.